1. Field of the Invention
The present invention is directed to a remotely controllable circuit breaker, and more particularly a remote controllable circuit breaker with a single set of breaker contacts which are forcibly opened and closed by a control signal remote from the circuit breaker independently of switching action by a manual handle of the breaker.
2. Description of the Prior Art
Circuit breakers of the above type which permit an remote control operation of opening the breaker contact are known in the art. Such a circuit breaker, for example, is described in U.S. Pat. No. 4,223,288. The circuit breaker utilizes a remotely controlled solenoid which, in response to a control signal from a location remote from the circuit breaker, actuates a movable contact arm carrying a movable contact away from a cooperative stationary contact for separation of the breaker contacts. The movable contact arm is operatively connected to a manually operated handle and an over-center tension spring to constitute a manually operable switching mechanism which, by the manipulation of the handle, is articulated with an over-center spring action between its ON position of closing the contacts and OFF position of opening the contacts. Said remotely controlled solenoid has an armature in abuttable engagement with the movable contact arm so that, when the solenoid is energized responsive to the remote control signal, the armature pushes the movable contact arm in the direction of disengaging the movable contact from the stationary contact against the biasing force of the over-center action spring. In this sense, the solenoid is to be additionally included or linked into the manually operable mechanism so as to add to complexity thereof and consequently render the fabrication thereof rather complicated.
In the meanwhile, it is quite possible that a consumer not knowing of the load interruption by such remote control signal tries in confusion, to uselessly manipulate the manual handle in an attempt to restore the load in series with the breaker. Such manipulation of the handle will naturally involve the movement of the movable contact arm between its ON condition and OFF condition with the over-center action of the spring included in the manually operable switching mechanism. Accordingly, with the above arrangement of actuating the movable contact arm linked to the handle and spring for separation of the breaker contacts by the remotely controlled solenoid, the solenoid cannot avoid being struck by the movable contact arm in its forward stroke from the OFF condition to ON condition due to the above handle manipulation by the unknowing consumer. With this result, the solenoid will suffer from the hammering action by the movable contact arm which action may damage the solenoid or cause the armature of the solenoid to bounce from its position of forcibly opening the breaker contacts into the position of momentarily closing the contacts, thus failing to stably keep the breaker contacts opened and rendering the operation of the remote controlled solenoid less reliable. To this end, the above prior circuit breaker has to include a separate latch means which is combined with the solenoid for mechanically holding the solenoid armature in the fixed position of opening the breaker contact so as not to be affected by the above hammering action, which further complicates the construction of the circuit breaker.